1. Field of the Invention
The present invention relates to a manipulator for medical use having an actuator unit and a working unit removable therefrom.
2. Description of the Related Art
According to laparoscopic surgery, it is customary to form a plurality of holes in the abdominal part of the patient, insert an endoscope and a forceps (or a manipulator) into the respective holes, and perform the surgical operation while images captured by the endoscope are being observed on a display monitor by the surgeon. Since such a laparoscopic surgical operation does not require the abdominal cavity to be opened, the burden on the patient is small and the number of days which the patient needs to recover and spend in the hospital until they are allowed to come out of hospital is greatly reduced. For these reasons, the laparoscopic surgical operation is expected to find an increased range of applications.
A manipulator system is composed of a manipulator body and a controller therefor, as described in Japanese Laid-Open Patent Publication No. 2004-105451, for example. The manipulator body contains an operating unit controlled by human and a working unit interchangeably removable from the operating unit.
The working unit (or an instrument) has a slender connecting shaft and an end working portion (also referred to as an end effector) disposed at the distal end of the connecting shaft. An actuator (a motor) for driving the end working portion via a wire is disposed in the operating unit. The wire is wound around a pulley in the vicinity of the proximal end. The motor in the operating unit is driven by the controller, whereby the wire is moved via the pulley.
The working unit does not contain an electron device such as a sensor in view of easily carrying out washing and sterilization. The positions or original points of the end working portion and the proximal end pulley cannot be directly detected, and the axial position of the end working portion is calculated based on rotation of the motor.
The working unit may be a gripper, a pair of scissors, an electric surgical knife, an ultrasonic surgical knife, a medical drill, or the like, and may be selected depending on a procedure in a laparoscopic operation. The working unit is removable from the operating unit, and when the working unit is attached to the operating unit, the pulley at the proximal end is engaged with a rotary shaft of the motor in the operating unit.
In such a system intended to connect a plurality of different working units to one operating unit, it is necessary to determine a motor phase as only one axial position, at which all the working units can be attached and detached (see Japanese Laid-Open Patent Publication No. 2004-105451, for example). The position is referred to as the original point (or the initial position).
Conventional manipulator systems are described in Japanese Laid-Open Patent Publication Nos. 2004-105451 and 2004-208922, etc.
In a system proposed in Japanese Laid-Open Patent Publication No. 2004-105451, it is unnecessary to take into consideration the motor excitation switching and electrical structure when the working unit is attached or detached.
In a system described in Japanese Laid-Open Patent Publication No. 2004-208922, a plurality of end tools (working units) are electrically attached and detached.
When surgery is traditionally performed, there is a long incision made so the surgeon can view and repair the internal parts of the patient. The long incision site can be a significant concern because it is subject to infection and is often the most traumatic and painful part of the patient's recover. In recent years, many surgeons have been using endoscopic tools and performing minimally invasive surgery, thereby vastly reducing the size of the incision.
Robotic tools have been developed to further improve the minimally invasive surgical process. These tools are highly specialized. They must perform the function that a surgeon would in a miniaturized manner. Surgeons perform many different functions on internal organs such as cutting, scraping, and suturing. Different surgical instruments are required for each of these functions. A different surgical device could be made for each surgical instrument, but it is most cost effective to simply change the surgical instrument mounted to the surgical instrument control unit for each function. To effectively implement interchangeability, each mounted surgical instrument must be safely and securely fastened to the surgical instrument control unit. Thus, there is a need for a device and a method for easily and reliably engaging surgical instruments with minimally invasive robotic surgical instrument control units. Further, there is a need for a mounting process that includes both engaging and locking steps such that surgical instruments can be used in a safe and efficient manner.
Further, the axial position of the end working portion is calculated based on, e.g. the original point of the motor. Thus, when a working unit is changed with another working unit during an operation, the other working unit needs to be precisely positioned at the original point. In other words, it is desirable that, when the working unit is detached from the operating unit, the working unit and the pulley are fixed at axial positions corresponding to the original point.